>>4310085what's the problem then?
let A and B be shapes in R^n
A and B can be defined as an equation
A={(r) in R ^n | r satisfies equation A}
A intersection B ={(r) in R^n| r satisfies equation A and B}
before rendering anything tell the engine to not render those points
for example in R^2, a circle and square would be
x^2+y^2=1:A
0<=x<=1, 0<=y<=1 :B
A intersection B ={(x,y) in R^2 | x^2+y^2=1, 0<=y,x<=1}